A. Field of the Invention
The present invention relates generally to high-speed data transmission, and more particularly, to a source synchronous data transmission link.
B. Description of Related Art
Conventional communication systems typically use either synchronous or asynchronous data transmission to transmit data from a transmitting system to a receiving system. Synchronous data transmission requires the transmitting and receiving systems to be synchronized with each other.
Conventional synchronous data transfer has the characteristic of requiring relatively constant time periods between successive events. Keeping time periods relatively constant, such as the time between successive bits, allows end systems to stay synchronized because the timing of successive events is predetermined.
To implement synchronous data transfer, the transmitting and receiving systems can be synchronized in a variety of ways. In some synchronous data transmission systems, for example, the transmitting and receiving ends share a common master clock. Because the end systems are synchronized with each other, synchronizing information does not need to be sent with the data. Although synchronous data transfer has many advantages, the precise clocks and timing requirements are very costly.
For asynchronous data transfer, data can be transmitted at irregular intervals. There is no clocking signal in asynchronous data transfer. Transferring data at irregular intervals, however, requires insertion of start and stop bits to mark the beginning and end, respectively, of the data stream. The receiving system uses the start and stop bits to determine when data is being received. Thus, although asynchronous data transfer is less costly in terms of clocks and maintaining timing, it lowers bandwidth because of the overhead of start and stops bits in the transmitted data. Therefore, conventional synchronous and asynchronous data transmission systems each have disadvantageous.
Accordingly, it is desirable to efficiently transmit data signals between devices without the disadvantages of conventional synchronous or asynchronous data transmission systems.